Slaty lady

January 27, 2018

Mike Powell and I were searching for Fine-lined Emerald dragonflies at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. As we were walking along one of many gravel trails at the park, I spotted a dragonfly perching atop an unusually tall grass stem.

16 SEP 2017 | Occoquan Bay NWR | Slaty Skimmer (mature female)

This individual is a mature female Slaty Skimmer dragonfly (Libellula incesta). Although Mike and I were disappointed we hadn’t found a Fine-lined Emerald, I was happy to shoot a photograph worthy of my Odonart Portfolio.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

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Red-spotted Purple butterflies

January 25, 2018

A Red-spotted Purple butterfly (Limenitis arthemis astyanax) was spotted during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

About a week later, another Red-spotted Purple was spotted during a walk around Mulligan Pond at Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA.

The appearance of Red-spotted Purple seems to be somewhat variable.

Copyright © 2018 Walter Sanford. All rights reserved.

Question Mark

January 23, 2018

A Question Mark butterfly (Polygonia interrogationis) was spotted during a photowalk at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Two field marks can be used to identify this butterfly. First, notice the row of four dark spots on the dorsal side of its forewings (highlighted in an animated GIF by Deb Platt).

Second, notice the silver-white question mark shape on the ventral side of its hind wings (highlighted in an animated GIF by Deb Platt).

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

Lunch time

January 21, 2018

A Blue-faced Meadowhawk dragonfly (Sympetrum ambiguum) was spotted at ~12:13 p.m. near a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male, eating an unknown species of winged insect.

25 OCT 2017 | HMP | Blue-faced Meadowhawk (male, eating)

The first photo is the scene-setter.

25 OCT 2017 | HMP | Blue-faced Meadowhawk (male, eating)

The last two photos are cropped so that the predator and prey are more prominent. The dragonfly barely moved from the first-to-last photos; the position of the butterfly/moth moved slightly as it was eaten.

25 OCT 2017 | HMP | Blue-faced Meadowhawk (male, eating)

Did you notice there are three insects shown in each photo? Perhaps the fly is an opportunist, waiting to clean-up the leftovers from the dragonfly’s lunch.

Copyright © 2018 Walter Sanford. All rights reserved.

Another black snake

January 19, 2018

A few days before I spotted the black snake featured in my last blog post, I saw another black snake at the same location in Huntley Meadows Park. In fact, I was so focused on searching for Great Spreadwing damselflies that I almost stepped on the snake!

This individual is probably an Eastern Ratsnake (Pantherophis alleghaniensis), as indicated by the appearance of its eyes.

22 OCT 2017 | Huntley Meadows Park | black snake

My close encounter of the startling kind shows the snake slithering along a carpet of leaf litter on the ground, heading toward one of several man-made brush piles near a vernal pool at a remote location in the park.

The last two photos show the snake moving around inside the brush pile. According to Kevin Munroe, former manager at Huntley Meadows Park, brush piles are “like a natural cupboard” where snakes hunt for small rodents.

22 OCT 2017 | Huntley Meadows Park | black snake

Eastern Ratsnakes have keeled scales, shown clearly in the full-size version of the preceding photo.

Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch. Source Credit: Keeled scales, Wikipedia.

Thanks to Timothy Deering for sharing this field marker in a comment on my last blog post.

22 OCT 2017 | Huntley Meadows Park | black snake

Related Resource: Black snake, a blog post by Walter Sanford.

Copyright © 2018 Walter Sanford. All rights reserved.

Black snake

January 17, 2018

A black snake was spotted basking on a man-made brush pile at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is either an Eastern Ratsnake (Pantherophis alleghaniensis) or Northern Black Racer (Coluber constrictor constrictor).

25 OCT 2017 | Huntley Meadows Park | black snake

According to Kevin Munroe, former manager at Huntley Meadows Park, Eastern Ratsnake can be differentiated from Northern Black Racer by looking at their eyes.

Northern Black Racers have a huge, all-black eye with an “eye-brow” ridge (makes racers look angry and somewhat dangerous all the time), while ratsnakes have noticeably smaller eyes with a black/white pupil/iris pattern (which makes them look more friendly/human). Also racers would never sit still long enough for you to take pictures, or at least it would be harder. Ratsnakes are pretty laid-back and easy to approach, while racers are very skittish and quick to flee. Ratsnakes mostly eat small mammals and young birds/eggs, while racers feed mainly on other herps like snakes, lizards and frogs. Ratsnakes are stealth/tracking hunters that smell out nests of young rodents and birds, while racers are active chasers/hunters/sprinters, which may be why they have such different personalities. Source Credit: Kevin Munroe.

25 OCT 2017 | Huntley Meadows Park | black snake

Based upon Kevin’s guidance, I think this individual is an Eastern Ratsnake.

25 OCT 2017 | Huntley Meadows Park | black snake

Another black snake was spotted on the ground, about 20 feet from the brush pile. The snake wasn’t moving, but the vegetation was too dense to get a clear view of the subject.

Related Resource: Another black snake, a blog post by Walter Sanford.

Copyright © 2018 Walter Sanford. All rights reserved.

Different point of view

January 15, 2018

The first photo shows “The Osprey’s at Belmont Bay,” as seen from the opposite side of Belmont Bay. “The Osprey’s” community shares a common boundary with Occoquan Bay National Wildlife Refuge, located to the left of this photo.

11 JAN 2018 | Prince William County, VA | The Osprey’s at Belmont Bay

The next photo shows the near shoreline of Belmont Bay. The bay is almost completely covered by ice after two weeks of below-freezing temperatures.

11 JAN 2018 | Fairfax County, VA | Belmont Bay

Notice the duck blind located in the water.

11 JAN 2018 | Fairfax County, VA | Belmont Bay

The following photo shows a dock and boat ramp located at the mouth of a small stream that is a tributary of Belmont Bay.

11 JAN 2018 | Fairfax County, VA | dock and boat ramp

The next photo is located upstream from the dock and boat ramp.

11 JAN 2018 | Fairfax County, VA | small tributary of Belmont Bay

The last photo shows a location far upstream from Belmont Bay. The stream is located at the bottom of a steep-sided valley.

11 JAN 2018 | Fairfax County, VA | small tributary of Belmont Bay

Tech Tip: I used my Panasonic Lumix DMC-FZ150 superzoom camera to shoot the landscape photos featured in this blog post. The camera was set for manual focus at the hyperfocal distance for an aperture of f/4, based upon the instructions provided in the excellent video tutorial by Graham Houghton, “Panasonic Lumix FZ camera easier manual focus method — super point-and-shoot tip.”

Copyright © 2018 Walter Sanford. All rights reserved.

Resting on a Coleman camp stool

January 13, 2018

In addition to my photography gear, I usually carry a Coleman camp stool when I go photowalking. The small, lightweight folding chair is good for resting while waiting for “the game to come to me.” The camp stool also enables me to get closer to subjects either on- or near the ground. And I think it’s easier to hold my camera rock-steady when I’m sitting on the chair with my elbows resting on my knees.

I like my Coleman camp stool. Some of my favorite insects like to rest on the camp stool too!

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

An Autumn Meadowhawk dragonfly (Sympetrum vicinum) was spotted near a vernal pool at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male, perching on a Coleman camp stool.

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

22 OCT 2017 | HMP | Autumn Meadowhawk (male, perching on a stool)

Copyright © 2018 Walter Sanford. All rights reserved.

Autumn Meadowhawk dragonflies (mating pairs, in wheel)

January 11, 2018

Several mating pairs of Autumn Meadowhawk dragonflies (Sympetrum vicinum) were spotted during a photowalk around a vernal pool at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA.

22 OCT 2017 | HMP | Autumn Meadowhawk (mating pair, “in wheel“)

Both pairs are “in wheel“: the male is on top; the female is on the bottom.

All odonates (dragonflies and damselflies) have a 10-segmented abdomen, numbered from front to back. Male dragonfly secondary genitalia, called hamules, are located in segments two and three (S2 and S3); female genitalia in segment eight (S8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

22 OCT 2017 | HMP | Autumn Meadowhawk (mating pair, “in wheel“)

Editor’s Note: Careful readers may be thinking “Hey, wait a minute — you said you spotted several mating pairs, but the post features photos of just two pairs.” Good catch! The photos of two more mating pairs didn’t make the final cut because the focus was slightly soft in all of those photos.

Copyright © 2018 Walter Sanford. All rights reserved.

Have you ever wondered…?

January 9, 2018

Have you ever wondered…

The preceding photo shows the “focal plane mark” on my Fujifilm X-T1 digital camera.

The same mark appears on my Canon EOS 5D Mark II DSLR, as shown on p. 16 of the “Instruction Manual.”

Minimum focusing distance versus working distance

The “minimum focusing distance” is the distance from the subject to the focal plane. The “working distance” is the distance from the front of the lens to the subject.

For example, the minimum focusing distance for the Fujinon XF80mm macro lens (shown above) is 246 mm (24.6 cm). The working distance is 98 mm (9.8 cm).

Magnification (or magnification ratio)

True macro lenses have a magnification ratio of at least 1:1, meaning the size of the subject is the same size on the focal plane (digital sensor).

For example, the digital sensor for the Fujifilm X-T1 is 23.6 mm wide by 15.6 mm high. At a magnification ratio of 1:1, a subject that is 15 mm (1.5 cm) long will be 15 mm (1.5 cm) wide on the digital sensor; expressed another way, the subject will fill ~64% of the frame width.

For a prime macro lens, maximum magnification of 1:1 is possible only at the minimum focusing distance; magnification is necessarily lower at longer focusing distances.

Adding an extension tube

Adding a Fujifilm MCEX-11 extension tube reduces the working distance to 89 mm (8.9 cm). It’s interesting to note the minimum focusing distance of 249 mm (24.9 cm) is essentially the same, with or without the extension tube.

The net effect of adding an extension tube is the magnification ratio is increased to a value greater than 1:1, say 1.2:1, so the subject appears slightly larger on the focal plane.

Related Resource: Adding an 11mm extension tube, a blog post by Walter Sanford.

Copyright © 2018 Walter Sanford. All rights reserved.


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